Medical device with a drive unit for a needle

ABSTRACT

The invention relates to a medical device, with a guide for the mounting of a needle, in particular, a puncture needle and a drive unit for a needle in the guide canal. The guide is divided into two sections and, arranged between the sections, is a drive unit for the, preferably friction, drive of the needle.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/DE01/01223 which has an Internationalfiling date of Mar. 30, 2001, which designated the United States ofAmerica and which claims priority on German Patent Application numbersDE 100 15 513.8 filed Mar. 30, 2000 and DE 100 15 510.3 filed Mar. 30,2000, the entire contents of which are hereby incorporated herein byreference.

FIELD OF THE INVENTION

The invention generally relates to a medical device with a guide for themounting of a needle, in particular a puncture needle, and with a driveunit for a needle located in the guide.

BACKGROUND OF THE INVENTION

In medicine, needle punctures of anatomical structures, whether fordiagnosis (biopsies) or for therapy (injections, drainage, etc.),represent a common and frequent intervention. Puncture needles are usedwhich are inserted through the patient's skin and advanced until theyreach a defined target (often a tumor or a metastasis). It is ofparticular importance in this respect that the needle is alignedprecisely with the target before insertion. Various imaging techniquescan be used to visually monitor the alignment procedure and the actualinsertion of the needle. The most common imaging methods used for thispurpose are ultrasound, fluoroscopy or computed tomography.

In fluoroscopy and computed tomography, X-rays are used to obtain theimages. Handling surgical instruments or a puncture needle near to theX-ray field or even within the X-ray field exposes the physician toconsiderable radiation levels. Although lead aprons and other protectivemeasures reduce the radiation dose, the radiation exposure of thephysician's hands themselves is still significant.

Devices taking over the manipulation of the instruments in the X-rayfield would be of help here. The physician would operate the devicesmanually or by remote control outside the X-ray field, depending onwhether the device concerned is a passive or active (motorized) device.

In the case of tissue removal, the needles used are either biopsy punchneedles (diameter 1 to 2.5 mm) for obtaining tissue samples forhistological examination, or fine needles (diameter ca. 0.8 to 1.4 mmwith a length of up to 20 mm) for aspiration biopsy for cytologicaltissue samples. Ever finer needles are used for injections.

The thinner and longer the needles however, the greater the danger ofthe needle buckling. When inserting the needle by hand, the physicianhas to take care to guide the needle steadily and without it buckling.For this purpose, fine needles are in most cases held tightly with onehand at the point of insertion and the other hand is used to apply thedriving force at the end of the needle.

If the needle is to be inserted by remote devices, that is to say drivenby a motor, then the danger of the needle buckling takes on particularimportance.

From EP-A-0 682 910, EO-A-0 595 291 and U.S. Pat. No. 5,882,294, it isknown in devices of the type, to divide the guide into two sections andto provide between both sections drive devices which cooperate withfrictional engagement to drive the needle.

From U.S. Pat. No. 4,383,532 and DE 94 16 957 U it is also known, by useof an articulated arm, to provide for pivoting about a defined point ofrotation in such a way that the articulated arm effects a pivotingmovement of the needle about a first axis and a second axis, and in eachcase in a plane containing the point of rotation.

SUMMARY OF THE INVENTION

An object of an embodiment of the invention is to make available adevice, in which the danger of the needle buckling is reduced. Oneaspect of an embodiment of the invention is the structural design of aneedle drive for remote-operated insertion of the needle without risk ofbuckling of the needle.

According to an embodiment of the invention, an object may be achievedby a medical device with a guide for the mounting of a needle, inparticular a puncture needle, and with a drive unit for a needle locatedin the guide. The guide is preferably divided into two sections.Preferably, the drive unit includes drive devices which are arrangedbetween the sections and which cooperate with the needle in order todrive the latter. Further, the needle is preferably pivotable about adefined point of rotation, wherein one end of the guide corresponds tothe point of rotation.

As a result of the drive device arranged between the two sections of theguide, the needle is guided optimally in that area in which driving ofthe needle takes place. This creates a homogeneous introduction of forceand practically rules out the danger of the needle buckling. The drivedevices preferably have at least one drive roller cooperating infrictional engagement with the needle, so that no changes need to bemade to the needle to be able to drive it. Thus, commercially availableneedles can be used instead.

BRIEF DESCRIPTION OF THE DRAWINGS

An illustrative embodiment of the invention is shown in the attacheddiagrammatic drawings, in which:

FIG. 1 shows a view of a medical device according to an embodiment ofthe invention,

FIG. 2 shows a perspective view of a detail of the device according toFIG. 1, and

FIG. 3 shows a view of the device according to FIGS. 1 and 2 in use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, a medical device according to an embodiment of the invention,labeled overall by reference number 1, is shown diagrammatically, with aneedle guide system 2 for a needle 3, e.g. a puncture needle, which, aswill be explained below, allows the needle 3 mounted in the needle guidesystem 2 to be pivoted three-dimensionally about a point of rotation R.

As will be seen from FIG. 1, the device 1 has an articulated arm 4 inthe form of a parallelogram drive, at whose free end the needle guidesystem 2 is arranged. Because of the design of the articulated arm 4 asa parallelogram drive, a pivoting about the axis A1, which is at rightangles to the plane of the parallelogram drive and therefore to theplane of the drawing in FIG. 1, through an angle ε likewise effects apivoting through the angle ε about an axis extending parallel to theaxis A1 through the point of rotation R defined by the geometry of theparallelogram drive.

The articulated arm 4 is additionally pivotable in a fixture 5 so as topivot in direction η about an axis A2 extending through the point ofrotation R.

Both axes A1 and A2 intersect and are perpendicular to one another.Since in addition the axis A2 extends through the point of rotation R,this represents as it were an invariable rotational point of the needle3 whose position is defined solely by the geometry of the construction.By superpositioning of both pivoting movements about the axes A1 and A2,the needle 3 can be pivoted three-dimensionally about the point ofrotation R which, in the medical application, is identical to the pointof insertion. One of the possible settings of the needle 3 is indicatedby broken lines in FIG. 1.

It will thus be apparent that, on the one hand, the needle 3 ispivotable by use of the articulated arm 4 about the defined point ofrotation R, the articulated arm 4 effecting a pivoting of the needle 3about a first axis in a plane containing the point of rotation R.Further, on the other hand, the articulated arm 4 is pivotable about asecond axis A2 extending through the point of rotation R, in the senseof a pivoting of the plane containing the point of rotation R about thesecond axis of rotation.

The pivoting movements about the axes A1 and A2 are effected by motordevices, the corresponding motors not being shown in the figures for thesake of brevity.

The fixture 5 is in turn arranged displaceably on a holding arm 6 whichfor example is passive, i.e. not driven by motor, but instead manuallyadjustable.

The drive unit of the device according to an embodiment of the inventionis described below with reference to FIGS. 1 and 2, which drive unitpermits buckling-free, motor-driven insertion of a needle 3 into thebody of a patient.

As will be seen from FIG. 2, which shows diagrammatically the needleguide system 2 and, in combination with FIG. 1, the principle of thedrive device of the needle 3, the core part of the needle guide system 2is a special guide cannula 7 which is secured at the distal end, i.e.the free end, of the articulated arm 4 and, as has been explained, canbe pivoted three-dimensionally within certain limits about the point ofrotation R corresponding to the point of insertion.

The function of the guide cannula 7 is to receive the needle 3 securelyand to guide it. The particular feature of the guide cannula 7 lies inthe fact that it is divided into two sections 7 a and 7 b, with drivemeans for the needle 3 being located between the sections 7 a and 7 b.

As exemplary drive means, the drive unit has two rollers 8 a, 8 b which,as is illustrated, are preferably provided with a grooved profile andbetween which the needle 3 is guided. As soon as they are driven, therollers 8 a, 8 b, designed in particular as rubber rollers, converttheir rotary movement by friction, i.e. by frictional engagement, into atranslational movement of the needle 3, so that the needle 3 can beinserted into a patient.

To apply the driving torque for the rollers 8 a, 8 b, the drive unit hasa servomotor 9 which, according to FIG. 1 in the case of theillustrative example described, is located in the area of the lowerhorizontal element of the articulated arm 4. Via a drive shaft 10 and,if necessary, additional (gearing) components not shown in FIG. 2, thetorsional moment is transmitted to the pair of rollers 8 a, 8 b via atoothed gear wheel 11. A uniform distribution of the torsional moment toboth rollers 8 a, 8 b is ensured via two toothed wheels 12 a, 12 b whichare connected directly to the rollers 8 a, 8 b.

The needle 3 is guided optimally in its drive area by means of the twosections 7 a and 7 b of the guide cannula 7 arranged tight on therollers 8 a, 8 b, which guarantees a homogeneous and uniformintroduction of force into the needle 3 and largely rules out the dangerof the needle 3 buckling upon insertion.

Also in the area of the point of insertion of the needle 3 which, as hasbeen mentioned, is identical to the point of rotation R, the danger ofthe needle 3 buckling upon insertion is largely precluded because theguide cannula 7 is arranged on the articulated arm 4 in such a way thatits one end corresponds to the point of rotation R. By this arrangementof the guide cannula 7, it is in fact ruled out that the needle canbuckle between drive and point of insertion.

This arrangement of the guide cannula 7 is also favorable because, inmedical application, the device must first be positioned in such a waythat the point of rotation R is located at the selected point ofinsertion, which is very easy because only the tip of the guide cannula7 has to be placed at the point of insertion.

The described structural design ensures, on the one hand, sufficientspace and freedom of movement, see the dimensions a and b indicated inFIG. 3, for versatile clinical application, the patient being indicatedby P and the target, e.g. a tumor, being indicated by Z in FIG. 3. Onthe other hand, the described structural design guarantees that thepuncturing is safe and free from buckling.

To be able to use needles of different diameters, the guide cannula 7can easily be made exchangeable (in a manner not shown). When usingrubber rollers, these generally have sufficient flexibility in order tobe able to use needles of different diameter at least to a limitedextent with the same pair of rollers.

As an alternative to the illustrative embodiment described, provisioncan be made for only one of the two rollers 8 a, 8 b to be driven.

The servomotor 9 and the drive shaft 10 can be arranged within one ofthe horizontal elements of the articulated arm 4 if the latter is oftubular design.

The drive unit according to the described illustrative embodiment is tobe understood in its details as constituting only an example. Theimportant thing is to use a guide which is divided into two sections,with drive means, particularly drive means with frictional engagement,being arranged between the sections for the needle.

This construction has the following advantages:

-   -   Buckling of the needle is largely ruled out both in the area of        the needle drive and in the area of the insertion site.    -   If the device is used with fluoroscopy, all components in the        X-ray field must be as radioparent as possible so as not to        generate shadows in the image. By means of the design as a        parallel drive, it is very easily possible to produce the front        area of the guide system from radioparent plastics, while the        motors and components of higher loading    -   made of metal are located outside the X-ray field.    -   With the parallelogram drive, it is possible for no hinges to be        present in the area of the point of rotation and there is        therefore sufficient space and freedom of movement for versatile        clinical application.    -   The whole construction can be made very compact, which in        particular permits use in CT. Alternative systems, by contrast,        often consist of arc-shaped structures, which in most cases are        very bulky.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A medical device, comprising: a guide for mounting of a needle, theguide being divided into two sections; and a drive unit for the needlewhen mounted in the guide, the drive unit including drive means arrangedbetween the two sections and cooperating with a mounted needle in orderto drive the mounted needle, wherein the mounted needle is pivotableabout a defined point of rotation and one end of the guide correspondsto the point of rotation, and wherein the guide is a guide cannula; andwherein the drive means includes a plurality of rollers, each rollerbeing directly connected to one of a plurality of toothed wheels, and atoothed gear wheel for driving the plurality of rollers via theplurality of toothed wheels.
 2. The medical device as claimed in claim1, wherein the drive means includes at least one drive rollercooperating in frictional engagement with the needle when mounted. 3.The medical device as claimed in claim 2, wherein the at least one driveroller includes at least one rubber drive roller.
 4. The medical deviceas claimed in claim 2, wherein the needle when mounted is pivotable byan articulated arm about a defined point of rotation, said articulatedarm effecting a pivoting of the needle about a first axis in a planecontaining the point of rotation.
 5. The medical device as claimed inclaim 4, wherein the articulated arm is in the form of a parallelogramdrive.
 6. The medical device as claimed in claim 4, wherein thearticulated arm is pivotable about a second axis extending through thepoint of rotation, in the sense of a pivoting of the plane containingthe point of rotation about the second axis of rotation.
 7. The medicaldevice as claimed in claim 6, wherein the articulated arm is in the formof a parallelogram drive.
 8. The medical device as claimed in claim 1,wherein the needle when mounted is pivotable by an articulated arm abouta defined point of rotation, said articulated arm effecting a pivotingof the needle about a first axis in a plane containing the point ofrotation.
 9. The medical device as claimed in claim 8, wherein thearticulated arm is pivotable about a second axis extending through thepoint of rotation, in the sense of a pivoting of the plane containingthe point of rotation about the second axis of rotation.
 10. The medicaldevice as claimed in claim 9, wherein the articulated arm is in the formof a parallelogram drive.
 11. The medical device as claimed in claim 8,wherein the articulated arm is in the form of a parallelogram drive. 12.The medical device as claimed in claim 1, wherein the guide is formounting of a puncture needle.
 13. The medical device as claimed inclaim 1, wherein the drive means is arranged tightly between the twosections.
 14. The medical device as claimed in claim 1, wherein eachsection of the guide encloses the needle when mounted.
 15. The medicaldevice as claimed in claim 1, wherein the drive unit includes at least apair of drive roller cooperating in frictional engagement with theneedle when mounted.
 16. The medical device as claimed in claim 15,wherein the at least a pair of drive roller includes at least a pair ofrubber drive roller.
 17. A medical device, comprising: a guide formounting of a needle, the guide being divided into at least twosections; and a drive unit for driving the needle when mounted in theguide, the drive unit having a drive means being arranged between atleast two of the sections and cooperating with a needle when mounted,wherein the needle when mounted is pivotable about a defined point ofrotation and one end of the guide corresponds to the point of rotation,wherein the guide is a guide cannula, wherein the needle when mounted ispivotable by an articulated arm, and wherein said drive unit includes aservo motor located on the articulated arm and transmitting torsionalmovement via a drive shaft to the drive means.
 18. The medical device asclaimed in claim 17, wherein the drive unit includes at least a pair ofdrive roller cooperating in frictional engagement with the needle whenmounted needle.
 19. The medical device as claimed in claim 17, whereinthe drive unit is arranged tightly between the two sections.
 20. Themedical device as claimed in claim 17, wherein each section of the guideencloses the needle when mounted.
 21. The medical device as claimed inclaim 17, wherein the drive unit includes at least one drive rollercooperating in frictional engagement with the needle when mounted. 22.The medical device as claimed in claim 21, wherein the at least onedrive roller includes at least one rubber drive roller.
 23. The medicaldevice as claimed in claim 17, wherein the needle when mounted ispivotable by an articulated arm about a defined point of rotation, saidarticulated arm effecting a pivoting of the needle about a first axis ina plane containing the point of rotation.
 24. The medical device asclaimed in claim 23, wherein the articulated arm is pivotable about asecond axis extending through the point of rotation, in the sense of apivoting of the plane containing the point of rotation about the secondaxis of rotation.
 25. The medical device as claimed in claim 23, whereinthe articulated arm is in the form of a parallelogram drive.